Fig. 62.
No. 1, is the wooden sword, with an elbow-joint at c. No. 2. Sword attached to board at k, and being allowed to fall from any angle shown by dotted-line, it strikes the block, w, outside the centre of percussion, p, and as there is unequal motion in the parts of the sword it bends down (or, as it were, breaks) at the elbow-joint, c. No. 3 displays the same model; but here the blow has fallen on the block, w, precisely at the centre of percussion of the sword, p, and the elbow-joint remains perfectly firm.
When a blow is not delivered with a stick or sword at the centre of percussion, a peculiar jar, or what is familiarly spoken of as a stinging sensation, is apparent in the hand; and the cause of this disagreeable result is further elucidated by fig. 63, in which the post, a, corresponds with the handle of the sword.
Fig. 63.
a. The post to which a rope is attached. b and c are two horses running round in a circle, and it is plain that b will not move so quick as c, and that the latter will have the greatest moving force; consequently, if the rope was suddenly checked by striking against an object at the centre of gravity, the horse c would proceed faster than b, and would impart to b a backward motion, and thus make a great strain on the rope at a. But if the obstacle were placed so as to be struck at a certain point nearer c, viz., at or about the little star, the tendency of each horse to move on would balance and neutralize the other, so that there would be no strain at a. The little star indicates the centre of percussion.
All military men, and especially those young gentlemen who are intended for the army, should bear in mind this important truth during their sword-practice; and with one of Mr. Wilkinson's swords, made only of the very best steel, they may conquer in a chance combat which might otherwise have proved fatal to them. To Mr. Wilkinson, of Pall Mall, the eminent sword-cutler, is due the great merit of improving the quality of the steel employed in the manufacture of officers' swords; and with one of his weapons, the author has repeatedly thrust through an iron plate about one-eighth of an inch in thickness without injuring the point, and has also bent one nearly double without fracturing it, the perfect elasticity of the steel bringing the sword straight again. These, and other severe tests applied to Wilkinson's swords, show that there is no reason why an officer should not possess a weapon that will bear comparison with, nay, surpass, the far-famed Toledo weapon, instead of submitting to mere army-tailor swords, which are often little better than hoops of beer barrels; and, in dire combat with Hindoo or Mussulman fanatics' Tulwah, may show too late the folly of the owner.